Shackle seal



FIG. 1 is a rear perspective view of a shackle seal showing my new design;

FIG. 2 is a top plan view;

FIG. 3 is a right side view, a view from the left side being a mirror image;

FIG. 4 is a bottom plan view;

FIG. 5 is a rear elevational view; and,

FIG. 6 is a front elevational view. 

The ornamental design for a shackle seal, as shown and described. 